One of Facebook's biggest threats won't be disappearing anytime soon

It posted 59% revenue growth, a 63% growth in ad revenue and 180%
growth in earnings per share compared to last year.

But, despite that growth, a big measure of
engagement for Facebook was actually down last quarter. The
ratio of daily active users to monthly active users fell by .5%
in the US and .2% in Europe, indicating that fewer people are
logging in daily.

It's the first time in nearly four years that the ratio has
fallen.

"It is worthy of a call-out since we are looking for early
evidence of usage transitioning to Snapchat," Brian Pitz,
analyst at Jefferies, said in a note to clients.

Facebook responds by saying that the time spent per user is
up by double digits.

"Snapchat could impact 3-9% of Facebook 2018 earnings
per share," Pitz said. "And that we could see
the (minimal) impact beginning as early as the fourth
quarter."

Snapchat grew it's users by 50% in 2015, and reaches 41% of
the 18-34 year old demographic in the US each day, according to the
service.

The core of Facebook's social platform is probably sheltered from
Snapchat's rise, as the two platforms serve different purposes.
But Instagram, Facebook's photo sharing platform, might not be so
lucky.

Still, it could be an early indication that users are
looking for an alternative to Facebook.

Pitz still rates Facebook a buy, and actually raised his
price target by $10 to $170, which means any impact Snapchat will
have on Facebook is still several quarters away at least.

But it's never too early to start looking for potential
risks for a company.